Signal.



c. 0. HARR|NGTON. SIGNAL.

. APPLICATION FILED IULYIZ. I9I3- I I I Patented 001;. 19, 1915.

2 SHEETS-SHEET I.

FIG. 1

WITNESSES I INVENTOR UNITED STATES PATENT OFFICE.

' CLINTON O. HARRINGTON, F EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR TO THE UNION; SWITCI-I'c SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A COR- PORATION OF PENNSYLVANIA.

SIGNAL.

- Patented Oct. 19, 1915.

Application filed July 12, 1913. Serial N 0. 778,783.

To all whom it may concern:

Be it known that I, CLINTON O. HARRING- TON, a citizen of the United States, residing at Edgewood Borough, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Signals, of. which the following is a specification.

. My invention relates to signaling, and particularly to apparatus for controlling signals of the type in which lamps are employed for giving indications both in daylight and at night.

My invention is particularly adaptable for use in connection with railway signals.

I will describe several forms of controlling apparatus embodying my invention, and will then point out the novel features thereof in claims; I

In the accompanying drawings, Figure 1 is a view, pa'rtly'diagrammatic, showing one form of signal having associated therewith one form of controlling apparatus embodying my invention. Fig. 2 is a view similar to Fig. l but showing a. modification of the controlling apparatus shown in Fig. l, and embodying my invention. Fig. 3 is a view, partly diagrammatic, showing a signal having associated therewith another form of controlling apparatus embodying my invention. Fig.4 is a view, partly diagrammatic, showing a signal having asso-' ciated therewith another form of controlling apparatus embodying my invention. Fig. 5 is a view similar to Fig. l but showing a modified form of the controlling apparatus shown therein. Fig. 6 is a view showing still another form of controlling apparatus embodying my invention. v

Similar reference characters refer to similar parts in each of the views.

When a lamp is employed as-a signal for giving. indications both in daylight and at night, such for example as a railway signal,

the lamp must, during daylight, be illumi nated at such intensityas to be clearly visible during the brightest sunlight and under the worst conditions of relative position of the sun and the signal, viz. when the signal is directly between the sun and the observer, or when the observer is directly between the signal and the sun. But it is undesirable that this high intensity of illumination be It is sometimes alsodesirable that the intensity of illumination of the lamps in such signals should be varied in accordance with variations of intensity of daylight, the lamps being more intensely illuminated on a bright day than on a cloudy day.

One feature of my invention is the provi- S10I1 of means for causing the illumination of the lamps 111 such signals at one intensity for daylight indications and at a lower intensity for night indications.

Another feature of my invention is the provision of means for varying the intensity of the illumination of the lamps in such sig' nals n accordance with variations of the 1ntensity of external light. 1

Referring first to Fig. 1, S designatesa' signal which may be a railway signal, comprising two electric incandescent lamps G and R; which lamps are provided respectively with lenses 2 and 2 for projecting the light from the lamps in beams along the trackway. These lamps are employed for giving indications both. in daylight and at night. The light projected from the two lamps usually differs in color, the light from lamp Gr usually being green and that from lamp R red; this coloring of the light may be effected in several different ways, for example, by forming the lenses 2 and 2 of green and red glass respectively. The representation of signal S being diagrammatic, the casing in which the parts are usually inclosed is omitted for the purpose of simplifying the drawing.

- Lamps G and R are provided with circuits which include a source of current 3, here shown as being a direct current battery. These circuits are controlled'by an armature contact 4* of an electromagnetic relay 4,

which may, for example, be a track relay in that contact l engages contact point 4", the green lamp G is illuminated and the red lamp R extinguished, and that when the relayis deenergized so that contact a engages contact point P the red lamp R is illuminated and the green lamp G extinguished. The circuits will be traced in detail hereinafter.

Included in the circuit of the lamps and R is a resistance 5, and the circuit is provided with a low-resistance shunt around this resistance 5. The voltage*at the lamps G and R, and consequently the intensity of illumination of these lamps, varies according as the low-resistance shunt is open or closed. This shunt is opened and closed by a relay device L which is responsive to variations of intensity of external light and which Twill now explain.

The relay device L comprises a base 6, preferably of metal, in which two metal rods 7 and 7 are fixed. These rods are preferably of the same metal, but if they are of different metals, they should be metals having substantially the same co-efiicients of expansion. Suitable means are provided for causing the two rods to expand and contract unequally during variations of the intensity of external light; as here shown, this is accomplished by blackening the surface of one rod 7 with any suitable materialvsuch as lampblack, and polishingthe surface of the other rod 7*. As is well understood, when the device is subjected to light, the blackened rod 7 will expand more than the polished rod 7 the reason being that a large propor-' tion of the light which strikes the blackened rod is absorbed by the lamp black and transmitted to the rod and transformed into heat, whereas the greater proportion of the light which strikes the polished rod is reflected therefrom. The temperature'of the blackened rod is therefore higher than that of the polished rod, so that the blackened rod expands more than the polished rod. The free ends of rods 7 and 7 a are provided with pins 10 and 10 respectively, which pins fit freely ductor as hereinafter explained. Owing to the length, of arm 8, any relative expansion of rods 7 and 7 will be greatly multiplied at the end 8 so that a small relative expansion of the rods will cause a considerable movement of end 8 of the arm.

The low-resistance shunt around resistance 5 is from wire 12-through wire 13, con- .wire 32, resistance 5 to battery 3. If relav 4 were deenergized so that contact 4 'l is closed, the circuit would be the same as just traced except that it would include lamp R instead of lamp G. The effect of resistance 5 is to cause the current in the circuit to be of such value that whichever lamp G or R is included in circuit is illuminated at a comparatively low intensity, this intensity being such that the rays from the lamp are not objectionable to an observer in total darkness. During bright daylight, however, rod

7 expands more than rod 7 so that arm 8 occupies the position shown in solid lines, in which position contact 81l is closed, so that the low-resistance shunt around resistance 5 is then closed. The lamp circuit is then the same as before, except that the low-resistance shunt is in parallel with re- 1 sistance 5. Lamp G or R, whichever is included in the circuit, is then illuminated at its, highest intensity, this intensity being sutficient to make the rays from the lamp clearly visible in the brightest daylight and under-the worst conditions of observation.

The relay device L is not responsive to variations of temperature to openor close contact 8-I1. The reason for this is that since both rods 7, 7 have the same, or substantially the same coeflicient of expansion, they expand and contract equally during variations of temperature. The movement of the free endsof the rods due to this contraction and expansion is not multipled by the arm 8 because this arm then moves parallel to itself, consequently, the movement of plate 8* is equal tothe movement of the free ends of the rods. This movement of plate 8? is so slight compared with the sensitiveness of the device as a whole that it does nota ffect the contact 8 11.

As hereinbefore stated, arm 8 is biased by gravity and by spring 9 to such position that contact 8 ll is closed. Hence, in'case of breakage of either of the'pins 10 or 10*, the contact 8 11 will be constantly closed and the lamps G and R will constantly burn at full brilliancy.

Referring now to Fig. 2, I have here I shown means for causing several degrees of intensity of illumination of the signal lamps G and R, ranging from the most intense illumination in bright daylight to the dimmest illumination at night. Tn Fig. 2 the as follows. In'Fig. 2 the circuits for lamps G and R are provided with a resistance 15 comprising three sections 15*, 15 and 15. The arm 8 is provided with a contact finger 8 which moves over a plate 16 having alternate strips of conducting and insulating material as shown in. the drawing. Each strip of conducting material on this plate is electrically connected with the resistance as shown. The width of the finger 8 is greater than the width of the strips of insulating material, so that in moving over plate 16 the finger always remains in contact with one conducting strip until after it has made contact with the next conducting strip,

The operation of the apparatus shown in Fig. 2 is as follows: During the brightest daylight, arm 8 occupies the position shown in full lines in the drawing, so that finger 8 then is in contact with the lowest conducting strip on plate 16. The circuit for lamp -(assuming relay 4 to be energized) isthen from battery 3 through contact 4 --4", lamp Gr, wire 32, spring 9, arm 8, finger 8 and lowest conducting strip on plate 16, wire 17 to battery 3. It will be seen that none of resistance.15 is included in this circuit, consequently, lamp G is illuminated at the highest intensity of its range. Of course, if relay 4 were deenergized, the circuit just traced would include lamp R instead of lamp G. Then as the daylight becomes less bright, finger 8 moves to the next conducting strip on plate 16 and leaves the' lowest conducting strip. The circuit for the lamps is then the same as before, except that it includes section 15 of resistance 15. Whichever lamp is included in the circuit then burns at somewhat less intensity than before. Similarly, as the daylight becomes still less bright, the finger 8 movesto the third conducting strip andleaves the second, so that the lamp circuit then includes resistance sections 15 and 15 in series, and whichever lamp-is included in the circuit ,then burns at still less intensity than before.

Finally, in very dim daylight or at night, the finger 8 moves from the third contacting strip to the fourth contacting strip so that the lamp circuit then includes the total resistance 15. Whichever lamp is included in the circuit is then illuminated at the lowest intensity of its range.

Referring to Fig. 3,1 have here shown another form of light-responsive relay device L adapted to control the signal lamps in the desired manner. In this view the signal S and the control of the circuits for the signal by relay 4 are the same as in Figs. 1 and '2. The relay device L shown in Fig. 3 is a pivotally mounted armature 21. This armature 21 is provided with two windings 22 and 23 (each represented diagrammatically by a single turn of wire) both of which windings are constantly energized from a J source of current 19, here shown as being a battery. The torques exerted on armature 21 by currents in these two windings are in opposite directions, that exerted by current in winding 22 being in the direction'of thearrow, and that exerted by current in winding 23.being inthe opposite direction. The circuits for the two windings are in multiple and include respectively a resistance 20 and a resistance 20 These resistances have the same percentage of variation of resistance per degree of change of temperature, or in other words, the ratio of their resistancesremains the same regardless of changes of temperature provided-the changes of temperature of the two resistances are equal. Pref erably the two resistances are of the samematerial. Means are provided for causing unequal variations of these resistances "due to variations of intensity of external light,

as here shown, this is accomplished by polishing' resistance 20 and blackening resistance 20. Hence, when agiven amount of light is falling on both resistances, resistance 20 will absorb more light than resistance 20 and the temperature of the former will, therefore, be higher than that of the latter, so that the resistance of the former will be higher than that of the latter. The'current in winding 22 will then be greater than that in winding 23 so that a torque will be exerted on armature 21 in the direction of the arrow. Fixed to armature 21' to move therewith is a contact arm 24, the outer end of which is adapted to'move into and out of engagement with ,a contact point 7 25. The armature 21 is, biased by a spring 27 to such position that arm 24 is in engagement. with a fixed stop 26, in which position contact 2425 is.open. As in Fig. 1, the lamp resistance 5 is provided with a shunt comprising wire 13, contact 2425 and wire 14.

The relay device L is so adjusted that at night and in dim daylight the values of the currents in windings 21 and 23 are such that the torques exerted on armature 21 are substantially equal, so that arm 24 1s then held against stop 26 by spring 27, and contact 2425 is open. The shuntaround re.-'

sistance 5 is then open, so that whichever of the lamps G or R is in circuit, depending on the position of relay contact 4, is illuminated at a comparatively low intensity. In bright daylight, however, the value of resistance 20 increases more than that of resistance 20, so that the value of the current in winding 23 decreases more than,that of the current in winding 22. The torque exerted by the current in winding 22 then exceeds that exerted by current in winding 23 by an amount suflicient to overcome the action of spring 27, and the armature 21 then moves and closes contact 24-25. The shunt around resistance is then closed, so that Whichever lamp Ur or R is in circuit is illuminated at its highest intensity.

Referring now to Fig. l, I have here shown another form of light-responsive relay device embodying my invention for opening and closing the low-resistance shunt around the lamp resistance 5. In this view, the low-resistance shunt is controlled by a suitable relay 28 which, as here shown, is a tractive relay. This relay 28 is provided with an energizing circuit including a source of current 29, here shown as being a battery, and aresistance 30, the value of which varies with variations of the intensity of light to which it is exposed. This resistance 30 may, for example, be selenium. As is well understood, the value of the resistance of selenium decreases as the intensity of the light increases, and vice-versa. The parts included in the energizing circuit for relay 28 are so adjusted that at ni ht and in dim daylight the resistance of t is circuit is such that relay 28 is open; the lowresistance shunt around resistance 5 is then open at contact 28 -28", so that whichever sufficient to cause this relay to close, thereby closing the low resistance shunt around resistance 5 at contacts 28 28 WVhichever lamp G or R is included in the circuit is then illuminated at its highest intensity.

Referring now to Fig. 5, the apparatus here shown is similar to that shown in Fig.

4: except that the energizing circuit 'for relay 28 includes a selenium cell 31. As is well understood, the'value of the electromotive force of a cell of this character increases as the light to which it is exposed increases and decreases as the light de-' creases. The energizing circuit for relay 28 is so adjusted that at night or in dim daylight, relay 28 is open, thereby opening the low-resistance shunt around resistance 5, so that whichever lamp Ur or It is included in circuit is illuminated at a comparatively low intensity. In bright daylight, however, relay -28 is closed, thereby closing the lowresistance shunt around resistance 5 at contacts 28 28 so that whichever lamp G or R is included in circuit is then illuminated at its highest intensity. g

In Fig. 6, the signal S and relay 4 are the same as in the preceding views, but the resistance 5 is of a material whose. value varies due to variations of the light to which it is exposed. This resistance may, for example, be of selenium, the resistance of which decreases as the light increases, and vice-versa. The circuit for the lamps is so adjusted that at night the current in whichever lamp .G or R is in circuit is such that the intensity of illumination is not so high as to be objectionable. Then as the intensity of daylight increases the value of resistance 5 decreases and the current in lamp G or R increases, so that the intensity of illumination of the lamps increases. NVith the apparatus shown in Fig. 6, the intensity of illumination of the lamps varies gradually according to variations of external light.-

Although I have herein shown and described only a few forms of controlling apparatus embodying my invention, it is understoodthat various changes and modifications may be made therein within the scope of the appended claims, without departing from the spirit and scope of my invention. Having thus described my invention, what I claim is:

1. In combination, a signal comprising a lamp adapted to give indications both in daylight and at ni ht, means for causingv illumination of sai lamp at one intensity for daylight indications and at a lower intensity for night indications, and means responsive to changes from daylight to darkness and vice-versa for controlling said means. I

2. In combination, a signal comprising a lamp adapted to give indications/[both in daylight and at night, means for causing a plurality of different intensities of'lllumination of said. lamp, an meansr'esponsive to variations of external light for controlling said means.

3. In combination, a signal comprising a "lamp, and means responsive to variations of daylight and at night, means for causing,

illumination of said lamp'at one intensity for daylight indications and at a lower intensity for night indications, and means responsive to external light for controlling said means.

6. In combination, a signal comprising an electric lamp adapted to give indications both in daylight and darkness, means for supplying currents of two different values to said lamp, and means responsive to external light for controlling saldmeans.

7 In combination, a signal comprising an electric lamp adapted to give indications both in daylight and darkness, means for supplying current to said lamp at one voltage for daylight illumination and at a lower voltage for night illumination, andmeans responsive to external light for controlling said means.

8 In combination, a signal comprising an electric lamp, a circuit for the lamp including a source of current and a resistance, a low-resistance shunt around said resistance, said shunt including a contact, and means responsive to variations of external light for opening and closing said contact.

9. In combination, a signal comprising an electric lamp adapted to give indications I bothin daylight and at night, two elements one of which is responsive to external light in greater degree than the other, and means controlled by relative variations of said elements in response to variations of external light for causing illumination of said lamp at one intensity for daylight indications and at a lower intensity for night indications.

10. In combination, a signal comprising a lamp adapted to give indications both in daylight and at night, two metal rods one of which is polished and theother blackened saidrods being exposed to external light, and means controlled by relative expansion of said rods due to'variations of external light for causing variations of intensity of illumination of said lamp. 7

11. In combination, a signal comprising a lamp adapted to give indications both in daylight and at night, two metal rods one of which is polished and the other blackened said-rods being exposed to external light, and means controlled by relative expansion of said rods for causing illumination of said lamp at one intensity for daylight indications and at a lower intensity for night indications.

In testimony whereof I aflix my signature in presence'of two witnesses.

I CLINTON O. HARRINGTON. Witnesses:

A. HERMAN WEGNER, MAX BRAURMAN. 

